The Ducks average 1.6 goals. That's last in the NHL. They are off two home games versus the Blues where they were outscored, 10-2. 
Oh, yes, this also is the Ducks' fourth game in six days. 
By contrast, the Kings are well rested. They last played on Thursday. The Kings are 3-2 in their last five games with victories against the Blues, Avalanche and Wild during this span.
The Kings are the better team, home and in the better spot. So this short price is worth laying.